Bacterial infections are significantly different than viral infections, though both may cause a foodborne illness and, in some cases, the symptoms may be the same. Bacteria, which are single celled living organisms, can cause bacterial infections. However, not all bacteria are harmful, in fact, many are beneficial and necessary. When harmful bacteria enter the body, they reproduce and produce toxins which damage cells in the body.

Viruses are not living organisms; they require the cells of a living host, be it human, animal, or plant. Viruses take over cells and cause them to produce more copies of the virus, often, eventually killing the host cell. The distinction between viruses and bacteria is especially important to treatment. Antibiotics combat bacterial infections; they do not work in treating viral infections. Furthermore, irradiation can aid in the elimination of many bacteria, but because viruses are significantly smaller they are not affected by the irradiation process.